Side swinging type mining machine having cutter drum and chain



Oct. 5, 1965 F. A. DELLl-GATTI, JR 3,21

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN 13 Sheets-Sheet 1 Filed March 9, 1961 INVENTOR.

Frank A. Delli-Gufli, Jr. BY

Oct. 5, 1965 F. DELLPGATTI, JR 3,

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN 13 Sheets-Sheet 2 Filed March 9, 1961 INVENTOR.

Frank A.Delli-GuHi,Jr. W W W 1965 F. A. DELLl-GATTI, JR 3, 3

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN Filed March 9, 1961 13 Sheets-Sheet 3 INVENTOR.

Frank A.De|li -Gufli Jr. WOZWA Oct. 5, 1965 F. A. DELLl-GATTI, JR 3,210,123

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN l3 Sheets-Sheet 4 Filed March 9, 1961 INVENTOR.

Frunk A.Delli-GOHi Jr. wf

Oct. 5, 1965 F. A. DELLl-GATTI, JR 3,210,123

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN 15 Sheets-Sheet 5 Filed March 9, 1961 .D m 4M d C 224 4 M mm ml 4 R g 4 P. e ml 4 n a w m 7 m Fig.l9.

INVENTOR.

Frunk A.Delli-Gutti Jr. BY W 5, 1965 F. A. DELLl-GATTI, JR 3,210,

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN Filed March 9. 1961 13 Sheets-Sheet 6 nnnnnnnn? U f" u uuuvu INVENTOR.

Frank A. Delli -GOHi Oct. 5, 1965 F. A. DELLl-GATTI, JR 3,210,123

SIDE SWINGINQ TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN Filed March 9, 1961 13 Sheets-Sheet 7 155 I56) v i lolb IOlu 660 C. 27 125a g INVENTOR.

Frank A. Delli GoHi Jr. BY

Oct. 5, 1965 F. A. DELLl-GATTI, JR 3,210,123

SIDE SWING'ING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN Filed March 9, 1961 15 Sheets-Sheet 8 X Fig.|8B.

lOlb

INVENTOR.

Frank A.Delli-GaHi,Jr.

1965 F. A. DELLl-GATTI, JR 3,210,123

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN 13 Sheets-Sheet 9 Filed March 9, 1961 INVENTOR. Frank A. Delli-GuHi, Jr.

/ awy Oct. 5, 1965 F. A. DELLl-GATTI, JR 3,210,123

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN Filed March 9, 1961 13 Sheets-Sheet 10 FIG. 23.

0 0 29 O O o [l a o o O 0 0 I 30' a O a 0 3 a 3 2| 0 c o o O O 232 f 50 INVENTORI FRANK A. DELLl-GATTI, JR.

BY WW ATTORNEY Oct. 5, 1965 F. A. DELLI-GATTI, JR 3,

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN Filed March 9, 1961 15 Sheets-Sheet 11 FIG. 27

INVENTORZ FRANK A. DELLIGATTI. JR.

ATTORNEY Oct. 5, 1965 F. A. DELLI-GATTI, JR 3,

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN l3 Sheets-Sheet 12 Filed March 9, 1961 mmN mm GE INVENTORI FRANK A. DELLl-GATTI. JR.

ATTORNEY Oct. 5, 1965 F. A. DELLI-GATT|, JR 3,210,123

SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN 13 Sheets-Sheet 13 Filed March 9, 1961 ATTORNEY United States Patent 3,210,123 SIDE SWINGING TYPE MINING MACHINE HAVING CUTTER DRUM AND CHAIN Frank A. Delli-Gatti, 5L, Bridgeport, W. Va., assignor to Charles E. Compton Filed Mar. 9, 1961, Ser. No. 94,644 11 Claims. (Cl. 299-64) This application is a continuation-in-part of application Serial No. 795,440 filed February 25, 1959, now abandoned.

This invention relates to mining machines and particularly to machines for recovering mineral deposits such, for example, as coal. Although the mining machine may be adapted to other uses it is primarily adapted and intended for the mining of coal and for purposes of explanation and illustration will be described as embodied in a coal mining machine.

The present machine may be used either in surface mining or in deep mining. In either type of mining the coal must be removed from the vein and conveyed to a delivery point. This involves breaking the coal in the vein into pieces of such size that they can be practicably conveyed to the delivery point. The breaking up of the coal in the vein may, as known to those skilled in the art, be effected either by blasting or by mechanical means. If the coal is blasted it has to be undercut in advance of blasting and the coal after blasting lies in a heap on the mine floor whence it must be picked up and conveyed to the delivery point. This is not an efficient operation, particularly under present conditions of high cost of mining and low coal prices.

The mining machine herein disclosed comprises a supporting structure upon which preferably two arms pivotally mounted to turn substantially in the same generally horizontal plane together with means for turning the arms between positions in which they extend generally away from each other and positions in which they extend generally alongside each other, two rotary cutting heads, one carried by each arm for rotation about a generally hori zontal axis, the heads substantially facing each other when the arms are in the second mentioned positions, and means for rotating the heads. The cutter head is a continuous circle of bits and cuts an uninterrupted arc wherein there is a smooth action with even load on all bits as compared to the standard boring machine which has segmented arms which cuts an interrupted are having shock loading. As the arms move in generally circular paths generally toward each other the rotating heads bite into and break up the coal and at the same time move the coal from both sides to a central location where the coal may easily be conveyed rearwardly or away from the working face. A conveyor is provided for conveying material generally longitudinally of the supporting structure from one end portion thereof and the two arms are preferably pivotally mounted on the supporting structure adjacent that end portion of the supporting structure so that the arms are disposed generally at opposite sides of the center line of the conveyor to turn substantially in the same generally horizontal plane. In operation of the machine the arms are turned between positions in which they extend generally away from each other and in a direction transverse of the center line of the conveyor and positions in which they extend generally alongside each other and in a direction generally parallel to the center line of the conveyor. By providing the rotary cutting heads for horizontal sweeping action which heads have continuous cutter contact action throughout its cutting operation with the coal vibration as well as wobble is eliminated providing for a more eflicient cut producing more marketable coal. In addition by providing a rotary cutting head of the type disclosed, shock is eliminated 3,216,123 Patented Oct. 5, 1965 providing for a continuous cutting action which removes the undesirable cyclic shock loads imparted to previously designed cutter heads. In addition thereto, the rotary cutter heads herein disclosed have cutters on their peripheral sides which permits the cutter head to side out by a milling action which is laterally to the longitudinal direction of the mining machine thereby providing for greater versatilty and flexibilty. This feature is particularly advantageous in making a lateral connection to the adjacent parallel passageway. Through the use of the rotary cutting head in the horizontal sweeping action a larger percentage of marketable coal is obtained as the cutting action is one of undercutting. From the placement of the cutter arms of the mining machine a greater amount of room to either side of the mining machine is achieved which permits greater maneuverability for the mining machine as well as auxiliary equipment used closely therewith.

The conveyor for conveying material generally longi tudinally of the mining machine preferably has sections at the respective ends thereof which are movable to a plurality of positions to enable the conveyor to receive and discharge material at various elevations and an intermediate section which is mounted in fixed position on the supporting structure.

The mining machine in the preferred form comprises a supporting structure, a conveyor extending longitudinally of the supporting structure, mining means at the forward end of the supporting structure for mining ma terial and delivering the same onto the conveyor, the mining means including a mounting member pivotally mounted on the supporting structure and extending forwardly therefrom with a rotary cutter head thereon cooperative with a cutter chain which circulates relative to the mined material and which chain is driven by the cutter head, roof bolting means carried by the supporting structure at a location adjacent the rear end of the mounting member, an operators control station disposed rear wardly of the roof bolting means and means extending from the mining means to the control station whereby an operator at the control station may control operation of the mining means. The machine provides a cutter chain which cooperates with the cutter head to increase the cutting capacity of the machine as well as removal of the marketable coal wherein the chain performs a conveying function as well as cutting function.

Accordingly, an object of this invention is to provide a new and improved coal mining machine of the combined cutting and loading type. 7

Another object of this invention is to provide a new and improved mining head for dislodging coal from. a solid seam.

A further object of this invention is to provide a new cutter head having conveying means integrated thereinwhich is mounted for horizontal pivotal swinging action.

A further object of this invention is to provide a new and improved cutter head having dual means coordinated. to be swung in a horizontal pivotal movement from the respective lateral sides of a mining machine towards the forward longtiudinal center line of the machine.

A further object of this invention is to provide a mining machine having a new and novel cutter head that cuts a mine vein laterally of the longitudinally extending mining machine as well as forwardly thereof.

A further object of this invention is to provide a mining machine with a novel cutter head means which mines a longitudinally extending mineral vein that is substantially Wider than the width of the mining machine in a continu ous operation providing a maneuverable clearance space to either side of the mining machine.

A further object of this invention is to provide a new and improved mining machine having lateral spaced cutter heads which are pivotally swingable horizontally toward the central longitudinal axis of the mining machine cooperative with auxiliary cutting means which moves the cuttings rearwardly to provide a mining machine with increased capacity.

A further object of this invention is to provide a new and improved mining machine with a pair of cooperative pivotally swingable non-vibratory cutter heads which are continuously in contact with the mineral vein without shock loading the cutter heads.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred embodiment thereof proceeds.

In the accompanying drawings there is shown a present preferred embodiment of the invention in which:

'FIGURE 1 is a plan view of a mining machine;

FIGURE 2 is a side elevational view of the mining machine shown in FIGURE 1 to slightly reduced scale;

FIGURE 3 is a plan view of the main frame or supporting structure of the mining machine showing how the means for carrying the cutting heads are connected thereto; the cutting heads, conveyor, motors, pumps, endless traction elements and other elements are omitted for clarity of showing of the parts illustrated in this figure;

FIGURE 4 is a vertical cross-sectional view taken on the line IVIV of FIGURE 3;

. FIGURE 5 is a plan view of the conveyor;

FIGURE 6 is a side elevational view of the conveyor;

FIGURE 7 is a vertical transverse cross-sectional view to enlarged scale taken on line VIIVII of FIGURE 6; FIGURE 8 is a vertical transverse cross-sectional View to enlarged scale taken on the line VIIIVIII of FIG- URE 6;

FIGURE 9 is a vertical transverse cross-sectional view to enlarged scale taken on the line IXIX of FIGURE 6;

FIGURE 10 is a vertical transverse cross-sectional view to enlarged scale taken on the line XX of FIGURE 3 with parts omitted for clarity of showing of the parts illustrated in this figure;

FIGURE 1 1 is a side elevational view with a portion cut away of one of the rotary cutting heads and the means whereby it is mounted;

FIGURE 12 is a top plan view of the structure shown in FIGURE 11;

FIGURE 13 is an end elevational view of the structure shown in FIGURES 11 and 12;

FIGURE 14 is a side elevational View of one of the endless traction elements upon which the machine is mounted and the means for mounting and driving the same;

FIGURE 15 is a vertical transverse cross-sectional view taken on the line XV-XV of FIGURE 14;

FIGURE 16 is a vertical transverse cross-sectional view taken on the line XVIXVI of FIGURE 14;

FIGURE 17 is a vertical transverse cross-sectional view taken on the line XVII-XVII of FIGURE 14;

FIGURES 18A and 18B together constitute a diagram showing one form of hydraulic circuitry for the mining machine;

FIGURE 19 is a diagram showing one form of hydraulic circuitry for controlling the piston in one of the head support tilting cylinders;

FIGURE 20 is a front elevational view of a tapered cutting head;

FIGURE 21 is a side elevational view of the tapered cutting head shown in FIGURE 20 and FIGURE 22 is a vertical longitudinal cross-sectional view taken on the line XXIII-XXIII of FIGURE 20;

FIGURE 23 is a plan view of a modified design of the forward portion of the mining machine shown in FIG- URES 1-22;

FIGURE 24 is a side elevational view of the forward portion of the mining machine shown in FIGURE 23;

FIGURE 25 is an enlarged side elevational view of the forward portion of the mining machine (FIG. 23) showing 4 the cutter head in outline and the idler adjustable chain supporting structure;

FIGURE 26 is a schematic plan View of the forward portion of the mining machine showing the cutter heads in laterally extended position at the commencement of a cut;

FIGURE 27 is a schematic plan view of the forward portion of the mining machine showing the cutter heads in their forward advanced position at the completion of a cut;

FIGURE 28 is an elevational view of a modified form of an idler adjustable chain supporting structure shown in FIGURE 25 with parts omitted for clarity of showing of the parts illustrated in this figure;

FIGURE 29 is an end elevational view in partial cross section of the chain supporting structure shown in FIG- URE 28 with parts omitted for clarity of showing of the parts illustrated in this figure.

FIGURE 30 is a side elevational view of the modified form of the idler adjustable cutter chain supporting structure shown in FIG. 28 in cooperative relationship with the rotary cutting head and cutter chain with certain parts omitted for clarity of showing the parts illustrated in this figure.

Referring now more particularly to the drawings, there is provided a welded steel frame or support structure designated generally by reference numeral 2. The supporting structure is elongated generally in the right and left direction viewing FIGURES 3 and 4. It comprises cross members 3a, 3b, 3c, 3d, 3e, and 3i and longitudinal side members 4a and 4b. The cross member 3] is elevated relatively to the other cross members for a purpose to be described and the side members 4a and 4b have at their left hand ends viewing FIGURE 4 upwardly extending portions 4:: and 4d, respectively, connected with the cross member 3f as will be described. The supporting structure is made up of steel plates and shapes welded together.

As an integral part of the supporting structure 2 there is a reservoir for hydraulic fluid, the reservoir being designated generally by reference numeral 5 and constituting side portions 5a and Sb, a rear portion 5c and a forwardly extending generally centrally located portion 511. The portion 5a communicates directly with the portion 50 which in turn communicates directly with the portion 512. The portions 5a and 5b are connected with the portion Ed by pipes 6. In FIGURE 4 the portion 5a! of the reservoir is shown as being open at a portion of its top, but when the base plate of the conveyor, presently to be described is applied and welded in place it closes the portion 5d of the reservoir. Consequently the reservoir for hydraulic fluid is completely closed and includes the portions 511, 5b, 5c, 5d and 6.

The side members 4a and 4b of the supporting structure have applied to their outer faces generally vertically extending angle members 7 for the purpose of supporting endless tract-ion elements upon which the mining machine is carried and which move it from place to place. Each of the endless traction elements is designated by reference numeral 8 and is trained about a fabricated steel frame designated generally by reference numeral 9 and including vertical plates 10 which when the frame 9 is applied to the supporting structure of the machine lie inside and adjacent the outwardly projecting legs of the angle members 7 at that side of the machine. Bolts 11 pass through the outwardly projecting legs of the angle members 7 and through the plates It) to fasten the frames 9 carrying the endless traction elements 8 to the supporting structure, it being understood that there is an endless traction element thus mounted to the supporting structure on each side thereof. Bolt holes 11a in the plates 10 and the outwardly projecting legs of the angle members '7 may be provided in equally spaced vertical arrangement as shown in FIGURE 16 so that the height above the bottoms of the endless traction elements 8 of the supporting structure 2 may be altered by matching up different bolt holes in the plates and angle members and applying bolts 11 therethrough.

Each of the frame portions 4c (FIG. and 4d of the supporting structure has extending inwardly therefrom a generally horizontal projection 12 has an upward extension 13, and a trunnion member 14 is journaled in bearings 15 in each upward extension 13 and the cooperating frame portion 4c or 4d (see particularly FIGURE 10). Fastened to the trunnion member 14 at each side of the machine is a mounting member 16 in the form of a lever extending longitudinally of the machine. Each mounting member 16 is adapted to be turned about the generally horizontal axis of its trunnion 14 by a piston operating in a cylinder 17 (on the left hand side of the machine looking forward) or 17a (on the right hand side of the machine looking forward) pivoted to the supporting structure at 18 and whose piston rod is pivoted to the mounting member 16 at 19.

Pivoted to each mounting member 16 by a generally vertical pivot pin 20 (FIGS. 3 and 4) is an arm 21 which projects generally horizontally to the left viewing FIG- URES 3 and 4. Each trunnion member 14 has an outward extension 22 terminating in a yoke 23 in which is trunnioned by pivot means 24 a cylinder 25 (at the left hand side of the machine) or 25a (at the right hand side of the machine). Each of the cylinder 25 and 25a is of the telescoping type known to those skilled in the art and its piston terminates in a piston rod 26. Each of the rods 26 is pivoted to the corresponding arm 21 by a pivot pin 27. The pistons in the cylinders 25 and 25a may be and preferably are operated simultaneously to turn the arms 21 in the same generally horizontal plane between positions in which the arms 21 extend generally away from each other as shown in phantom lines in FIG- URE 1 and positions in which such arms extend generally alongside each other as shown in solid lines in FIGURE 1 and in FIGURE 3. The fact that the cylinders 25 and 26a are carried by the yokes 23 which in turn are connected with the trunnion members 14 enables the pistons in the cylinders 25 and 25a to move the arms 21 back and forth regardless of the angular positions of the mounting members 16.

Pivoted to each arm 21 by a generally horizontal pivot member 28 is a head support 29 in which is mounted for rotation about a generally horizontal axis a cutting head designated generally by reference numeral 30. Each head support is adapted to be turned about the axis of its pivot member 28 by a piston operating in a cylinder 31 (at the left hand side of the machine) or 31a (at the right hand side of the machine) which is pivoted to the corresponding arm 21 at 32, the piston rod 33 of the piston operating in each of the cylinders 31 and 31a being pivoted to the corresponding head support 29 at 34.

Fluid pressure means are provided for maintaining the piston in each 'of the cylinders 31 and 31a against substantial movement in either direction in selected locations in the cylinder so that the angular relationship between the arm 21 and the head support 29 will remain constant for any desired setting. FIGURE 19 shows the hydraulic connections to the cylinder 31 and the means for maintaining the piston against substantial movement in either direction. Similar means are provided in connection with the cylinders 17, 17a, 25 and 25a for maintaining the pistons in those cylinders against substantial movement in either direction in selected locations in the cylinder. Such means insure a smooth and uninterrupted operation of the machine and inhibit undesired movement of mounting members 16, arms 21 and head supports 29 in either direction.

Each of the rotary cutting heads comprises a generally circular base member 35 which as shown in the drawings is a steel plate having an offset mounting ring 36 at its center, the mounting ring having centrally thereof a circular opening 36a. Each mounting ring 36 is fitted over a hub 43 which in turn is mounted on a cutting 6 head driving shaft 38 driven by a transmission 39 in a housing 40 carried by one of the head supports 29, and each mounting ring 36 is fastened to the corresponding hub 43 by bolts 42 (FIG. 11). The respective transmissions are driven by hydraulic motors 41 (at the left hand side of the machine) and 41a (at the right hand side of the machine) respectively. Each hub 43 is keyed to the corresponding driving shaft 38 by a key 44. When a head is to be replaced it is not necessary to remove the hub 43 but the nuts may be removed from the bolts 42 enabling removal of the head. Another head may be applied in its place and the bolts 42 and the nuts applied to them put in place to fasten the head to the hub 43.

The rotary cutting head shown in FIGURES 11, 12 and 13 has annularly arranged projecting means in the form of a generally annular body 45 having therein openings 46 through which mined material is adapted to pass. Cutting means 47 are carried by the body 45 at the axial extremity thereof remote from the base member 35, and additional cutting means 48 are carried by the body 45 intermediate its axial extremities and project outwardly. Further cutting or breaking means 49 are carried by the plate 35 and positioned generally within the space defined by the generally annular body 45.

FIGURES 20, 21 and 22 show a tapered cutting head in which a generally annular body 45' is connected at one axial extremity with a circular base member or plate 35', the body 45' being of greater diameter at the axial extremity thereof remote from the plate 35 than at the axial extremity thereof adjacent such plate. The tapered head carries cutting means 47 analogous to the cutting means 47, cutting means 48' analogous to the cutting means 48 and cutting or breaking means 49' analogous to the cutting or breaking means 49. The cutting means 48 relatively adjacent the axial extremity of the generally annular body 45 adjacent the plate 35 project outwardly farther than the cutting means 48' relatively adjacent the axial extremity of the body 45' remote from the base member 35 so that the outer extremities of the cutting means 48 considered collectively form substantially a cylinder.

Pushing means are floatingly mounted on the arms 21 and on the head supports 29 and are adapted to engage the ground and partake of limited up and down movement relatively to the members carrying them as they move over uneven ground.

Each arm 21 (FIGS. 11 and 13) has spaced apart downwardly projecting lower portions 50 between which is positioned the upper portion of a pusher 51 having teeth 52 extending downwardly from its lower portion. The pusher 51 is guided between the spaced apart portions 50 for generally up and down movement. Bolts 53 pass through the portions 50 and through vertically elongated slots 54 in the pusher 51. The thickness of the pusher 51 is slightly less than the distance between the opposed faces of the downwardly projecting portions 50 so that the pusher can partake of limited up and down movement relatively to the portions 50 and to the arm 21 as it moves over uneven ground. A pusher 55 is similarly connected to each head support 29 and functions in the same way. The pushers 51 and 55 act cooperatively to push material ahead of them upon the inward sweeping movement of the head supports while the rotating heads remove the coal from the vein and break it and also assist in moving it inwardly or toward the center line of the mining machine. Although the teeth 52 are shown only on the bottoms of the pushers 51 similar teeth may be provided on the bottoms of the pushers 55. The teeth aid in removing irregularities in the mine floor and contribute to the formation of a level surface for the advance of the mining machine.

There is provided a conveyor which is positioned substantially along the longitudinal center line of the mining machine. The conveyor has a pan 56 (FIG. 5) in which the coal is conveyed rearwardly or toward the right viewing FIGURE 1 by an endless chain 57 carrying pusher flights 58. The chain is driven by a sprocket 59 so that its upper reach moves toward the right viewing FIGURE 1 and its lower reach moves toward the left. The lower reach of the chain moves in a space 60 below the pan 56. The conveyor has a plurality of tandem connection sec tions 61, 62, 63 pivotably connected at their respective adjacent ends. The conveyor has sections 61 and 62 at the respective ends thereof which are movable to a plurality of positions to enable the conveyor to receive and discharge material at various elevations. The central section 63 of the conveyor is mounted in fixed position in the machine. The bottom of the conveyor section 63 forms the cover for part of the portion d of the fluid reservoir. The section 61 is pivoted to the section 63 at 64 and the section 62 is pivoted to the section 63 at 65. The section 61 is swung upwardly and downwardly about its pivot 64 by pistons operating in cylinders 66 and 66a pivoted to the cross member 3 of the supporting structure, the piston rods 67 being connected with the conveyor section 61 by means of a cross bar 68. The conveyor section 62 is similarly swung up and down about the pivot 65 by a piston operating in a cylinder 69 pivoted to the supporting structure at 70, the piston rod being connected with the conveyor section 62 at 71.

The driving sprocket 59 for the endless conveyor element is fixed to a shaft '72 (FIG. 9) which is driven by a pair of hydraulic motors 73 and 74 connected with the ends of the shaft 72.

At the conclusion of a cycle of operation of the mining machine the heads are in the position shown in solid lines in FIGURE 1. To commence the next cycle the heads are swung outwardly by turning the arms 21 about the pivots 20. Normally the rotary cutting heads are continuously driven although if desired they may be stopped when the arms 21 are swung outwardly. When the arms 21 have reached their outward positions so that the heads have their cutters 47 facing toward the wall of coal to be mined the mining machine is moved forward or toward the Wall of coal (the working face) upon the endless traction elements 8 a distance equal to a fraction of the diameter of the rotary cutting heads. The exact distance which the machine is moved forward at the beginning of the cycle depends on the type of coal being mined. Generally the forward advance will be through a distance of the order of one-third to one-half the diameter of the rotary cutting heads. The heads rotate in such a direction that when they are in the position shown in FIGURE 1 the upper portions of the heads move toward the working face and the lower portions of the heads move away from the working face. The heads are in the dotted line position of FIGURE 1 when the machine is moved forward at the beginning of the cycle. With the heads rotating the arms 21 are then swung from the dotted line position of FIGURE 1 to the full line position of FIGURE 1. The heads bite into the coal at the working face, breaking and removing the coal from the face and at the same time moving the coal toward the center line of the machine. Much of the coal which is removed from the face and broken by the head passes out of the heads through the openings 46 in the heads. The heads may also have openings at their rearward portions through the base member 35 or the base member 35 may be replaced by spokes with spaces between them as above indicated. The coal which drops down from the heads is pushed toward the center line of the machine by the pushers 51 and 55. The coal is taken by the conveyor and delivered rearwardly through the center of the machine and below the cross member 3 and is discharged at the rear end of the conveyor which may be elevated to a desired position to discharge coal into a desired receptacle such as a shuttle car or conveying means.

When the heads are partaking of an inward movement in the mining of coal it is desirable that the mounting members 16 be substantially horizontal so that the pivots will be substantially vertical. Under those conditions the heads will swing in a substantially horizontal plane whereas if the mounting members 16 are tilted the heads will not swing in a horizontal plane and their operation will be less etficient. The elevation of the heads is adjusted by the pistons in the cylinders 31 and 31a without disturbing the generally horizontal movement of the heads during a mining operation. It may be desirable to make two passes for each position of the machine, one pass at the top of the seam and the other at the bottom of the seam, the elevation of the heads being determined by the pistons in the cylinders 31 and 32. In the second pass the pushers will clean up the shaft floor adjacent the working face.

The supporting structure carries roof bolting means 75 at a location adjacent the rear ends of the mounting members 16 and at the opposite sides of the supporting structure as shown in FIGURE 3. The operators control station is disposed rearwardly of the roof bolting means at the right hand side of the machine looking forward as shown in FIGURE 1. Each of the roof bolting means 75 may have controls in its own immediate area as known to those skilled in the art. Each of the roof bolting units 75 comprise two hydraulic cylinders and a hyraulically driven chuck as known to those skilled in the art. The hydraulic cylinders of the roof bolting unit at the left-hand side of the machine are designated 76 and 77, respectively and the hydraulic cylinders of the roof bolting unit at the right hand side of the machine are designated 76a and 77a, respectively. The hydraulically driven chuck at the left hand side of the machine is driven by a hydraulic motor 78 (FIG. 3) and the hydraulically driven chuck at the right hand side of the machine is driven by a hydraulic motor 78a. The roof bolting units 75 may be purchased from a manufacturer of such units and no novelty is claimed for the units per se. However, their positioning as described and as shown in the drawings is novel and of great utility as they are disposed forwardly of the operators station and close to the working face. This provides for the safety of the operator and greatly contributes to the efiiciency of the mining operation.

Mounted atop the supporting structure are two motive units Wand 79a (FIG. 1) which are shown as being electrical motors. The motors through connections which will be described below drive hydraulic pumps for supplying hydraulic fluid under pressure for the operation of the various components of the machine.

Each of the endless traction elements 8 is driven by a sprocket 80. Coacting with each sprocket 80 is an idler wheel 81 provided with a take-up adjustment 82 whereby the slack in the chain may be removed. Each sprocket 80 is fixed to a shaft 83 to which is also fixed a sprocket 84. Meshing with each sprocket 84 is a sprocket chain 85 for driving the corresponding endless traction element, the sprocket chain 85 being driven by a sprocket 86 fixed to a shaft 87 driven by a fluid motor 88 (at the left hand side of the machine) or 88a (at the right hand side of the machine) through a transmission 89. Each motor 88 or 88a and the associated transmission 89, drive chain 85 and related mechanism are all disposed substantially within the space surrounded by the corresponding endless traction element.

Referring now to FIGURES 18A and 188 each of the motors 79 and 79a drives four pumps. Motor 79 drives a single pump 103 and a double pump 105 from the left hand motor shaft extension viewing FIGURE 18B and a double pump 168 from the right hand shaft extension. Coupled in line vw'th the right hand shaft extension is a variable delivery pump 102. Motor 79a drives a single pump 104 and a double pump 106 from the left hand motor shaft extension viewing FIGURE 18A and a double pump 107 from the right hand shaft extension. Coupled in line with the right hand shaft extension is a variable delivery pump 101.

The delivery pump 101 drives through hydraulic conduits or lines 101a and 10112 the hydraulic motor 41a which furnishes the power to rotate the right hand cutting head. The variable delivery pump 102 drives through hydraulic conduits or lines 102a and 102b the hydraulic motor 41 which furnishes the power to rotate the left hand cutting head. The cutting heads may be driven at any desired speed as each of the variable delivery pumps 101 and 102 can deliver from gallons per minute hydraulic fluid under pressure to the capacity of the pump.

The cylinders 25a and 25 receive their hydraulic power from the double pumps 104 and 103 respectively. They are controlled through valve blocks 112 and 111 respectively. Pump 103 delivers hydraulic fluid under pressure through line 117 to valve block 111. Valve 111a of valve block 111 controls flow through lines 118 and 119 to the cylinder 25. Pump 104 delivers hydraulic fluid under pressure through line 120 to valve block 112. Valve 112a of valve block 112 controls flow through lines 121 and 122 to the cylinder 25a.

Cylinders 31 and 31a which control elevation of the cutting heads are connected to valve blocks 111 and 112 respectively. Pumps 103 and 104 supply hydraulic fluid under pressure to cylinders 31 and 31a respectively through valve 1110 of valve block 111 and valve 112c of valve block 112. Valve 1111: delivers hydraulic fluid under pressure through lines 123 and 124 to cylinder 31 and valve 1120 delivers hydraulic fluid under pressure through lines 125 and 126 to cylinder 31a. A counterbalance valve 124a for a purpose presently to be described is disposed in line 124; the portion of line 124 between the valve 124a and the cylinder 31 is designated 124. Five other counterbalance valves 119a, 122a, 125a, 127a and 1290 are similarly disposed in the circuit in relation to cylinders 25, 25a, 31a, 17a and 17.

Cylinders 17a and 17 are connected to valve blocks 112 and 111 respectively. Pumps 103 and 104 also control the supply of hydraulic fluid under pressure for cylinders 17 and 17a through valve 11% of valve block 112 and valve 111b of valve block 111, respectively. Valve 111k delivers hydraulic fluid under pressure through lines 129 and 130 to cylinders 17 and valve 1121) delivers hydraulic fluid under pressure through lines 127 and 128 to cylinder 17a.

In one of the supply lines for each of cylinders 17, 17a, 25, 25a, 31 and 31a is disposed a counterbalance valve presently to be described.

The cylinders 66 and 66a work in unison to raise and lower the conveyor section 61. They are controlled by valve 110c of valve block 110 through lines 131 and 132. Hydraulic fluid under pressure for valve block 110 is furnished by pump 106 through line 133.

Cylinders 17, 17a, 25, 25a, 31 and 31a are of the double acting type while cylinder 69 is of the single acting type. Pressure is needed only to raise and hold the conveyor section 62, gravity being relied upon to lower that conveyor section. Cylinder 69 is supplied with hydraulic fluid under pressure through line 134 from valve 1090 of valve block 109. Valve block 109 receives its hydraulic fluid under pressure from pump 105 through line 135.

The endless traction elements 8 are driven by the hydraulic motors 88 and 88a. Motor 88a drives the righthand endless traction element and is controlled by valve 110a of valve block 110 through lines 136 and 137, hydraulic fluid under pressure being supplied by pump 106 through valve block 110 as above stated. Motor 88 drives the left hand endless traction element and is controlled by valve 109a of valve block 109 through line 138 and 139, hydraulic fluid under pressure being supplied by pump 105 through valve block 109 as above stated.

The hydraulic motors 73 and 74 are both coupled to the shaft 72 which carries the sprocket 59 and being so coupled those motors need to be synchronized. Motor 74 is controlled by valve 11% of the valve block 110 and motor through lines 140 and 141 respectively. Should the pressure of the hydraulic fluid fall below the requirements in either of valve blocks 109 and a by-pass line 142 near the hydraulic motors 73 and 74 permits the pressure within the lines and 141 to balance. Also, should either of the motors 73 and 74 tend to overrun the other due to an increase in pressure in its supply line the increased pressure will also be by-passed throughv line 142 to the other hydraulic supply line, again balancing the pressure. Should one of the pumps 105 and 106 fail the conveyor would continue to operate. Failure of the pump 106 would prevent operation of the right hand endless traction element driving motor 88a and the loss of one-half the normal supply of hydraulic fluid under pres sure for conveyor motors 73 and 74 and would also prevent operation of the cylinders 66 and 66a. Failure of pump 105 would prevent operation of the left hand endless traction element driving motor 88 and the loss of onehalf the normal supply of hydraulic fluid under pressure for conveyor motors 73 and 74 and would also prevent operation of the cylinder 69. Such loss of operation of one or the other of the pumps 105 and 106, however, would not prevent completion of an operative movement of the arms carrying the cutting heads and removal of the mined material.

Motors 780 and 78 receive their hydraulic power from double pumps 107 and 108 through lines 143 and 144 and valve blocks 115 and 113 respectively. Valves 115a and 113a of blocks 115 and 113, respectively, furnish the hydraulic power to hydraulic motors 78a and 78 through lines 145, 146, 147 and 148.

The hydraulic cylinders 77a and 77 which operate the mast used to stabilize the roof bolting units receive their hydraulic power from double pumps 107 and 108 through lines 149 and 150 and valve blocks 116 and 114 respectively. Valves 116a and 114a of blocks 116 and 114 furnish the hydraulic pressure to cylinders 77a and 77 through lines 151, 152, 153 and 154, respectively. The hydraulic cylinders 76a and 76 which raise the hydraulic motors 78a and 78 enabling the drilling or bolting operation on the roof receive their hydraulic power from double pumps 107 and 108 through lines 149 and 150 and valve blocks 114 and 116. Valves 116 h and 1141) of blocks 116 and 114 furnish the hydraulic power to cylinders 76a and 76 through lines 155, 156, 157 and 158, respectively.

One of the supply lines for each of the cylinders 17, 17a, 25, 25a, 31 and 31a has therein acounterbalancing valve whose purpose is to maintain the piston in the cylinder against substantial movement in either direction in selected locations in the cylinder. By way of illustration the counterbalancing valve used in connection with the cylinder 31 will be described.

Referring to FIGURE 19, hydraulic fluid under pressure delivered through line 117 from pump 103 is controlled by valve 111c. When the cutting head is to be raised the valve 111 0 is operated to cause the fluid under pressure to pass to the counterbalance valve 124a through the line 124; the fluid under pressure enters the valve 124a through port 124e. The valve 124a has a spool 1245 which is spring biased to remain in the position shown in FIGURE 19, i.e., its lowermost position in the valve. Spring 1240 is compressed by adjusting screw 124d and the spring pressure on the spool 124b is adjusted by turning the adjusting screw 124d in or out. The hydraulic fluid under pressure entering the port 124s of the valve 124a passes around the spool 1241b and forces open a spring loaded check valve 124) and continues its flow through the valve 124a, passing out through port 124g and through line 124 to the piston rod side of the piston within the cylinder 31, forcing the piston toward the right viewing FIGURE 19 and expelling hydraulic fluid from the right hand end of the cylinder, causing the fluid to flow through the line 123 to the valve 111c whence it is delievered back to the reservoir 5.

To lower the cutting head the valve 1116 is operated to cause the hydraulic fluid under pressure entering the valve through the line 117 to flow through the line 123 and enter the cylinder 31 at the right hand end thereof, forcing the piston in the cylinder 31 to the left viewing FIGURE 19 and causing the hydraulic fluid at the left hand end of the cylinder to be expelled under pressure through line 124 and into the valve 12451. through port 124g. The hydraulic fluid being directed through passage 124h in the valve 124a is delivered to the bottom of the spool 12411 to rise, opening the port 124g to port -124e and all-owing the hydraulic fluid to continue on through line 124 to valve 111c, whence it flows back to reservoir 5. In each of the above described operations raising and lowering the cutting head is accomplished by the action of the piston Within the cylinder 31, the hydraulic pressure being sufliciently high to override the pressure of the spring 1240 above the spool 124b and also the spring 124m beneath the check valve 124 One of the positions of valve 1110 is such that fluid under pressure entering through line 117 is allowed to pass freely through the valve while both the line 123 and the line 124 are closed. Such position of the valve may be termed the normal position. After the cutting head has been moved to a desired position by manipulation of the valve 111c as above described the valve is moved to normal position. Fluid under pressure is maintained in a now closed system having equal pressure on both sides of the piston in the cylinder 31. The spool 124i; and the check valve 124 prevent any displacement of the hydraulic fluid from the left hand side of the piston and the valve 111cprevents any movement of hydraulic fluid from the right hand side of the piston.

The spring 1240 governs the pressure required to shift the piston to the left within the cylinder 31 and the spring 124m governs the pressure required to shift the piston to the right Within the cylinder 31.

A modification of the rotary cutting head is shown in FIGS. 23-27 inclusive, wherein a pair of spaced elongated horizontally extendings arms 21' are suitably pivotably mounted at their rear end by vertically extending pivot pins 20 to the respective spaced pair of mounting members 16 in the same manner as arms 21 of the original embodiment are pivotably connected thereto and heretofore described in detail. The intermediate portion of each arm 21 is suitably pivotably connected to piston rods 26' of hydraulic jacks or telescopic cylinders 25' of a type well known in the art. The hydraulic jacks 25 may be and are preferably operated simultaneously to swing or pivot the arms 21' in the same horizontal plane in the same manner as the arms 21 of the original embodiment shown in FIGURE 1. If desired, only one arm 21' may be swung independently of the other arm. Cylinders 25' as cylinders 25 and 25a are carried by the yokes 23 which in turn are connected with the trunnion members 14 (FIG. which enables the pistons in the cylinders 25 and 25 to move the arms 21' as well as arms 21 back and forth regardless of the angular positions of the mounting members 16.

Pivotably mounted on the forward end of each arm 21' for movement in a vertical plane by a generally horizontal pivot member 28 is a head support 29' in which is mounted for rotation a cutting head designated generally by reference numeral 30'. Each head support 29' is suitably adapted to be rotatably adjusted about the axis of pivot member 28 by a hydraulic cylinder 31', which cylinder 31' is suitably pivotably connected by pivot member 231 (FIG. 24) to a downwardly projecting lower portion 50 of each arm 21 with the rod portion 232 of cylinder 31' being suitably pivotably connected by pivot member 233 to the lower portion of head support 29 of each cutting head 30' (FIG. 24).

Fluid pressure means are provided for maintaining the pistons in the respective cylinders 31 against movement and in rigid adjusted positions by similar means as cutting head 30 of the original embodiment of FIGS 1-19 in a manner similar to that shown in FIG. 19 previously described.

Each rotary cutting head 30' is constructed'in a manner similar to cutting head 3t previously described wherein a suitable circular support member 35 (FIG. 23) is suitably rotatably mounted relative to head support 29' to be desciibed.

As shown in FIG. 25 the rear end portion of each arm 21' has a support member 23d suitably rigidly mounted thereon in an upwardly extending position with an idler chain sprocket 237 suitably rotatably mounted at the uppermost end thereof for a purpose to be described. The intermediate portion of each arm 21' has downwardly depending L-shaped member 238 suitably rigidly secured thereon with the vertically extending portion of the L-shaped member 238 being suitably secured thereto and with the forward horizontally extending portion 239 suitably rotatably supporting an idler sprocket 24d mounted therein at the outermost end thereof as on an axle 241. Suitably rotatably mounted upon the axle 241 is a guide bracket 243 supporting a pair of forwardly extending chain guideways 245 for suitably guiding a cutter chain in a manner to be described. Suitably mounted on the lower portion of vertically extending portion of the L-shaped member 238 is a pair of chain guideways 245' which extend in a longitudinal direction substantially in line with a line drawn tangent to the lower portions of chain sprockets 237 and 240. The upper intermediate portion of each arm 21 has an upwardly extending bracket 252 suitably rigidly secured thereto. Only the elements relative to the one arm will be explained however it will be understood that other arm (21) is similarly constructed.

A longitudinally extending flat support member 250 has its rear end portion suitably pivotally mounted by a horizontally extending pivot pin 251 to the upwardly extending bracket 252 for pivotal movement relative thereto as well as relative to arm 21'. The forward end portion of flat support member 250 suitably rotatably support an idler chain sprocket 255 for a purpose to be described. An elongated link connecting member 256 has one end (upwardly extending as shown in FIG. 25)

suitably pivotably connected to the intermediate portion of flat support member 250 and the other end (downwardly extending as shown in FIG. 25) suitably pivotally connected to a bracket 29 which bracket 29" is suitably connected to the upper intermediate portion of head support 29'. As cutter head 30 is adjusted in an upwardly clockwise direction (FIGS. 24 and 25 by hydraulic jack 31 about pivot pin 28, link connecting member 256 exerts a rotative force on flat support member 250 causing support member 250 to rotate clockwise about pivot pin 251 thereby swinging idler sprocket 255 upwardly into the position indicated by phantom lines in FIG. 25. Similarly, chain guide member 245 is pivoted about pivot pin 241 in a clockwise direction by a cutter chain to be described.

Rotary cutting head 30' (FIG. 24) is similar in construction to the rotary cutting head shown in FIGS. 11, 12 and 13 of the original embodiment wherein a circular support member 35 (FIG. 23) is suitably mounted over a suitable hub for rotation relative to a mounting head support 29' with the support member 35" mounted on a driving shaft which is suitably driven by transmission means 39" in a manner well understood in the art. Each respective transmission means 39" is driven by a hydraulic motor 41 in the same manner as described in the original embodiment for rotatably driving cutter head 30. It is to be understood that other power means including electric motors may be used.

Suitably mounted on support members 35" and concentrically therewith is an annularly arranged body member 45" having openings 45" therein through which mined material is adapted to pass as disclosed in the original embodiment and as is well understood in the art. Cutting means 47" are carried by the body member 45" at the axial extremity thereof remote from the support member 35" and additional cutting means 48" are carried by the body 45" intermediate its axial extremities which cutting means 48" project radially outwardly therefrom. The circumferential periphery of support member 35" lying closely adjacent transmission means 39" has a plurality of sprocket teeth suitably rigidly secured thereto, which sprocket teeth are coplanar with idler chain sprocket 255, idler chain sprocket 237 and idler chain sprocket 240. A closed loop cutter chain 235 is suitably mounted upon the respective id-ler chain sprockets 255, 237, 240 and the sprocket teeth of the support member 35" for continuous circulating motion as is well understood in the art. Cutter chain 235 has cutter bits 235' suitably mounted in sockets along the cutter chain, which cutter bits 235' extend in the same general direction as the cutter bits 47" mounted on the extremity of the rotary cutting head 30. The forward portion of cutter bits 47" extend forwardly and radially outwardly beyond the outer limits of cutter bits 235' of the cuttter chain 235 such that the outermost limits of travel of the cutter bits 235' by the cutter chain 235 do not travel the full extent to which cutter bits 47" travel on the rotary cutting head 30 thereby maintaining a clearance space therebetween. Thus the primary cutting is done by the cutter bits 47 on cutter head 30. The cutting done by the cutter chain 235 in addition to the trimming action (best seen in FIG. 25) is that between the rotary cutting head 30' and idler sprocket 255 as well as that between the lower portion of rotary cutting head 30' and idler sprocket 240. In addition to this cutting action cutter chain 235 performs a conveying action which will be more fully described hereinafter. Pushing means 51 are mounted on the lower projecting portions 50 of each arm 21' and are floatingly mounted in the same manner in which pushers 51 are mounted on the arms 21 of the head support 29 wherein the pushing means 51 are adapted to engage the ground and partake of limited up and down movement relatively to the members carrying them as they move over uneven ground.

The operation of the modified embodiment shown in FIGS. 23-27 inclusive is very similar in manner to the operation of the original embodiment wherein the commencement of a cycle is shown in FIG. 26 wherein the cutting heads 30 are located in an outwardly extended position so that when the arms 21' have reached their laterally extended position, the heads of the cutters 47 face toward the wall of the coal to be mined. The mining machine is then moved forward or towards the wall of the coal of the working face upon the endless traction elements 8 a distance equal to a fraction of the diameter of the rotary cutting heads. With the cutting head 30' rotating the arms 21' are then swung from the position shown in FIG. 26 to the positions shown in FIG. 27 wherein the heads 30' bite into the coal at the working face, break and remove the coal from the face as they are swung inwardly toward the longitudinal central axis of the machine. While cutter chain 235 is circulated by the rotation of cutting head 30', it performs a cutting action on the mine face between the rotating cutting head 30' and the idler sprocket 255 as well as between head 30' and idler sprocket 240 while its lower portion conveys the cut coal rearwardly towards the central conveyor 57 for movements rearwardly of the machine onto shuttle cars or other mineral moving equipment. In addition to the conveying action by the cutter chain 235 the pusher 51' simultaneously moves over the uneven ground and pushes coal inwardly toward the head supports to aid in the removal of coal while the rotating heads remove the coal from the seams. The conveying action of the chains materially increases the capacity of the machine since there is no tendency of loose coal to pile up towards the forward center of the mining machine. A side cutting action which is principally a milling action is particularly important in making a break through to an adjoining parallel passageway wherein the lateral radially extending cutter bits 48" on the body member 45" of rotary cutting head 30' are positioned closely adjacent the lateral walls of a mine passageway so that as the mining machine is pivoted about the longitudinal central axes by advancing the thread on one side of the mining machine while applying the brakes on the other side, the cutter bits 48 of the cutting head 30 mill a recess and a laterally extending clearance space so that after a suflicient lateral clearance has been cut away the mining machine may be propelled into a suitable position to attack the lateral entranceway into a full passageway to connect an adjacent parallel passageway.

A modification of the chain guide means as shown in the embodiment of FIGS. 23-27 inclusive is shown in FIG. 28 which is principally a parallelogram type linkage mechanism wherein a pair of spaced upwardly extending brackets 280 and 281 respectively are suitably secured to the upper portion of arms 21' respectively. An elongated upwardly extending arm link member 282 has its lower end portions suitably secured to the upper portion of bracket 281 by a horizontally extending pivot pin 283 and its upper portion suitably supporting by a pivot pin 284 a sprocket wheel 275 for rotation thereon. An elongated crank member 285 has its intermediate portion suitably secured by a horizontally extending pivot pin 286 to the upper portion of upwardly extending bracket 280. Crank member 285 extends and is parallel to link member 282 with the upper portion of link member 285 suitably supporting for rotation a sprocket wheel 279 by a horizontally extending pivot pin 287 connection therewith. A horizontally extending link member 277 suitably joins the upper end portions of crank member 285 and link member 282 through the respective pivot pins 284 and 287 to thereby require simultaneous movement of one crank member upon movement of the other link member or vice versa. Suitably secured to the upper portion of link member 277 is a guide member 300 having guideways thereon substantially parallel to the longitudinal extending axes of link member 277 for guiding a cutter chain in a manner to be described. The lower portion of link member 285 has its lower extremity suitably pivotally secured to rod 291 of a hydraulic jack 290 by a horizontally extending pivot pin 289. Hydraulic jack 290 has its cylindrical portion suitably secured by horizontally extending pivot pin 292 to a bracket 294 which is suitably mounted closely adjacent the intermediate portion of bracket member 281. As shown in FIG. 28 hydraulic cylinder 290 is shown in the retracted position wherein the vertically extending crank and link members 285 and 282 are respectively parallel with each other and normal to the horizontally extending link mem ber 277 which extend therebetween. Upon extension of jack member 290 the lower portion of crank member 285 is swung in a clockwise direction about pivot pin 286 thereby swinging the upper portion of crank member 285 similarly in a clockwise direction and moving idler sprocket 279 clockwise. Similarly link member 282 is likewise moved clockwise through the link member 277, which suitably connects the two members 282 and 285. In this motion sprocket wheels 275 and 279 move the same amount and in the same direction maintaining their parallel relationship so that as the cutter chain 235 previously described, is guided by the respective idler sprockets 275 and 279 in a true horizontal manner therebetween at all times, regardless of the position in which rotating cutting member 30 is moved so that as the roof of the mine is cut by the rotary cutting head 30' and the cutter chain 235, the roof is left in substantially a horizontal extending plane.

FIG. 30 discloses the relationship of the rotary cutting head 30' previously described in cooperation with the cutter chain 235 and the chain guide means shown in FIG. 28 and described hereinabove. In this embodiment 

1. A CUTTING HEAD COMPRISING AN ELONGATED ARM SUPPORT HAVING A FORWARD END; A CUTTER DRUM MOUNTED ON SAID FORWARD END OF SAID ARM SUPPORT FOR ROTATION RELATIVE THERETO ABOUT A GENERALLY HORIZONTAL AXIS SUBSTANTIALLY NORMAL TO THE LONGITUDINAL AXIS OF SAID ARM SUPPORT; SAID CUTTER DRUM HAVING A FORWARD PORTION; CUTTER ELEMENTS MOUNTED SUBSTANTIALLY IN A CONTINUOUS LINE PERIPHERALLY AROUND SAID FORWARD PORTION OF SAID DRUM; SPROCKET TEETH MOUNTED CIRCUMFERENTIALLY AROUND SAID DRUM SPACED REARWARDLY FROM SAID FORWARDLY PORTION; MEANS CARRIED BY SAID ARM SUPPORT FOR ROTATING SAID CUTTER DRUM; CHAIN GUIDE MEANS MOUNTED ON SAID ARM SUPPORT FOR ROTATION RELATIVE THERETO ABOUT A GENERALLY HORIZONTAL AXIS; A CUTTER CHAIN CARRIED BY SAID CHAIN GUIDE MEANS AND SAID SPROCKET TEETH FOR MOVEMENT THROUGH AN ENDLESS ORBITAL PATH IN A SUBSTANTIALLY VERTICAL PLANE. 